Method and apparatus for in situ product recovery

ABSTRACT

A method of obtaining a compound may include adding a substrate to a medium in a reactor, and reacting the substrate in the reactor to form the compound. A first stream is separated from the reaction liquid through a first membrane. A second stream is separated from the reaction liquid through a second membrane. The first membrane is a filtration membrane and the second membrane is configured for liquid-gas or liquid-liquid extraction The first membrane and the second membrane are at least partially immersed in the medium and are moved relative to the reactor during the separation steps.

CROSS-REFERENCES

The following applications and materials are incorporated herein, intheir entireties, for all purposes: U.S. Nonprovisional patentapplication Ser. No. 16/642,829, filed Feb. 27, 2020.

TECHNICAL FIELD

The present disclosure is related to methods and apparatuses forobtaining compounds, in particular organic compounds such as esters oramides, or organic solvents such as butanol or acetone. In particular,the present disclosure is related to methods and apparatuses forseparating reaction products including the compound (continuously) fromthe reactor medium.

INTRODUCTION

The production of esters or amides often involves producing water or analcohol such as methanol as a by-product. Since these reactions areequilibrium reactions, removing the by-products will shift theequilibrium to the right hand side, increasing product yield. Variousoptions exist for withdrawing the by-products water and/or alcohol, suchas using desiccants (e.g., molecular sieves), using a stripping gas, orby pervaporation. The use of desiccants is problematic during attemptsof process upscaling, since they tend to pulverize, or cause problems inthe downstream processes. The stripping gas in most cases entrains alarge part of any volatile compounds present in the reactor.

The use of pervaporation for removing water and/or alcohol appearspromising, but requires a profound control of process conditions. In apervaporation unit, temperature and concentration gradients must beminimized, otherwise leading to losses in flux. To avoid these problems,a high degree of cross-flow is applied in order to minimize thesegradients. This however requires a high energy input.

Early in the 20th century, the microorganism Clostridium acetobutylicumwas found to convert carbohydrate containing feedstocks into acetone,ethanol and n-butanol, as described in U.S. Pat. Nos. 1,315,585, and2,386,374. The method has been referred to since as the acetonen-butanol ethanol (ABE) fermentation process.

As generally known, and for example described in WO2013/086458 andWO2015/002913, n-butanol is an important industrial chemical, useful forexample as a solvent, as a feedstock chemical in the plastics industry,as a fuel additive, as an ingredient in formulated products such ascosmetics, and as a food grade extractant in the food and flavorindustry. Moreover, as a fuel, n-butanol has several advantages overethanol. For instance, while n-butanol can be made from the samefeedstocks as ethanol, it is, unlike ethanol, compatible with gasolineand diesel at higher ratios. Furthermore, n-butanol can also be usedalone as a pure fuel in existing cars without modifications, it has beenproposed as a building block to make jet fuel, etc.

A major drawback of n-butanol, however, is its toxicity to the producingculture in the ABE fermentation process, leading to cell inhibition.This is for example discussed in WO2013/086458 and EP 2283141. Becauseof such end product toxicity, solvent productivity is limited and thefinal concentration of product on a volume basis is low as well.Consequently, energy-intensive distillation operations are used,negatively affecting the economics of recovery of the differentproducts. The high purification cost was one of the major reasons whythe ABE fermentation was to a large extent abandoned during the 1950sand 1960 s and replaced by petroleum based chemical plants forproduction of n-butanol and acetone. As such, each year 10 to 12 billionpounds of n-butanol are produced by petrochemical means. However, thedepletion of today's fossil fuel stocks, the fluctuations in fossil fuelprice and security of energy sources are the driving forces behind thecurrent revival in n-biobutanol production. Accordingly, there is a highdemand for efficient and sustainable methods for the production ofn-butanol.

As nowadays there is an interest in development of technologies that userenewable resources for fuel production, the ABE fermentation isattracting renewed interest. However, solutions have to be found toavoid or reduce the n-butanol toxicity leading to cell inhibition andthe associated low productivities and high purification costs.

In the art, it has already been proposed to alleviate the productinhibition by complementing the fermentation process with in situproduct recovery (ISPR) technologies, such as adsorption, pervaporation,gas stripping, or liquid/liquid extraction. In this way, n-butanol isremoved from the fermentor as it is produced, thereby allowing themicroorganism to produce n-butanol at higher productivity.

WO 2011/160030 for example utilizes liquid-liquid extraction as ISPR ina method and system for efficiently producing a fermentative productalcohol such as n-butanol.

DE 102011080611 describes a method for separating volatile compoundsfrom fermentation broths. Organophilic pervaporation membranes aremounted inside a fermentation reactor to withdraw volatile compoundsfrom the reactor. A second stream is withdrawn from the reactor andpassed over a filtration membrane to obtain a permeate comprising waterand smaller molecules, while the retentate comprises biomass,undissolved particles and non-fermentative macromolecules and ispartially recycled to the reactor.

Despite these efforts, the above methods still remain quiteenergy-intensive, in particular because they require performing pumpswhich provide for sufficient cross-flow streams on the membranes toavoid fouling and concentration and temperature gradients. Furthermore,substantial peripheral components are required around the reactor inorder to obtain the above efficiency improvements.

SUMMARY

It is therefore an aim of the present description to provide methods andapparatuses which overcome the above drawbacks. In particular, it is anaim to provide methods and apparatuses which are more efficient inproducing such compounds. It is furthermore an aim of the presentdescription to provide methods and apparatuses which have a reducedcomplexity and/or allow for simplifying downstream processing.

According to a first aspect, a method comprises adding a substrate to amedium, such as a reaction liquid, comprised in a reactor and reactingthe substrate in the reactor to form a compound, such as an ester, anamide, or an organic solvent such as acetone and/or butanol.Advantageously during the reacting step, a first stream is separated orwithdrawn from the medium through a first membrane, advantageously asemipermeable membrane. The first stream comprises first products.Advantageously, a catalyst is mixed with the medium in the reactor, andthe first membrane is configured for retaining the catalyst.Advantageously simultaneously with separating the first stream, a secondstream is separated or withdrawn from the medium through a secondmembrane, advantageously a semipermeable membrane. The second streamcomprises second products distinct from the first products. Either thefirst products, or the second products may comprise the compound. Thefirst stream and the second stream are withdrawn separately from thereactor.

According to an aspect, the first membrane and the second membrane,which are advantageously (at least partially) immersed in the medium,are moved relative to the reactor during the steps of separating thefirst stream and separating the second stream. Advantageously, the aboveseparation steps are carried out in parallel, e.g. simultaneously. Thefirst membrane is advantageously a filtration membrane, e.g. amicrofiltration or ultrafiltration membrane. The second membrane isadvantageously configured for liquid-gas or liquid-liquid extraction,e.g. a pervaporation membrane, or a contactor membrane respectively.Advantageously, the first and second membranes are mounted to respectivesupport frames which are configured to turn on a common pivot axis orseparate pivot axes arranged in a fixed position relative to thereactor.

According to a second aspect, an apparatus may be configured to carryout a method according to the above aspects. The apparatus comprises areactor, a first membrane unit and a second membrane unit. The firstmembrane unit is a filtration unit, advantageously comprising one ormore filtration membranes. The second membrane unit advantageouslycomprising one or more membranes configured for liquid-gas orliquid-liquid extraction, respectively, such as a liquid-gas(pervaporation) or liquid-liquid (membrane contactor) extraction unit.The reactor comprises a reactor vessel, a substrate supply port, andeither one or both of a first outlet port and a second outlet port. Thefirst membrane has a first surface communicating with the reactor vesseland a second surface, opposite the first surface, communicating with thefirst outlet port. The second membrane has a third surface communicatingwith the reactor vessel and a fourth surface, opposite the thirdsurface, communicating with the second outlet port. The first membraneis advantageously configured for transport of one or more firstcompounds from the first surface to the second surface, e.g. the firstmembrane is a semipermeable membrane. The second membrane isadvantageously configured for transport of one or more second compoundsfrom the third surface to the fourth surface, e.g. the second membraneis a semipermeable membrane. According to an aspect, the first membraneand the second membrane are arranged inside the reactor vessel.According to another aspect, either one or both of the first membraneand the second membrane is moveably arranged relative to the reactorvessel. Advantageously, the first surface and the third surface areaccessible in parallel from the reactor vessel. Advantageously, thefirst membrane and the second membrane are mounted in the reactor vesselsuch that they are at least partially immersed in a reaction liquid whenin use.

The apparatus can comprise first and second support frames to which thefirst membrane and the second membrane are respectively fixed. The firstand second support frames can be pivotally arranged relative to thereactor vessel, e.g. they can turn on a common pivot axis or separatepivot axes arranged in fixed position relative to the reactor vessel.

In some examples, an apparatus may include: a reactor, comprising afirst reactor vessel, a substrate supply, a first outlet and a secondoutlet, a filtration unit comprising a first membrane having a firstsurface communicating with the first reactor vessel and a secondsurface, opposite the first surface, communicating with the firstoutlet, and a liquid-liquid or liquid-gas extraction unit comprising asecond membrane having a third surface communicating with the firstreactor vessel and a fourth surface, opposite the third surface,communicating with the second outlet, wherein the first membrane and thesecond membrane are arranged inside the first reactor vessel, andwherein the first membrane and the second membrane are arranged to moverelative to the first reactor vessel.

By moving the membranes relative to the reactor, less pumping energy isrequired for sustaining a desired cross flow over the membrane surface.Furthermore, by appropriately maintaining the medium in motion relativeto the membranes simplifies the requirements for substrate supplycontrol, such as for temperature and concentration gradient control.Temperature gradients are minimized, and concentration gradients over asurface of the membranes can be minimized. A further advantage of theapparatuses and processes described herein is that they are inherentlysafer because no associated (external) loops with high cross flows areinvolved. There is no or less external piping which may be prone toleakage and/or which may expose maintenance operators to (potentially)toxic products. A further advantage is that they allow for integratingthe membranes within the reactor vessel resulting in reactors with smallfootprints, taking much less space in comparison to prior art designs.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure will now be described in more detailwith reference to the appended drawings, wherein same reference numeralsillustrate same features and wherein:

FIG. 1 represents schematically an apparatus integrating two separatemembrane units in the reactor according to aspects described herein;

FIG. 2A represents a horizontal respectively vertical cross section of areactor according to aspects described herein, wherein two membraneunits are mounted on rotating supports within the reactor vessel;

FIG. 2B represents a cross section view along section line A-A;

FIG. 3 represents a (horizontal) cross section of an alternative reactorcompared to FIG. 2A, wherein the two membrane units are mounted on asingle rotating support within the reactor vessel;

FIG. 4A represents schematically an apparatus integrating two separatemembrane units in the reactor according to aspects described herein;

FIG. 4B represents schematically an alternative of the apparatus of FIG.1A, in which a third membrane unit is further provided in the reactor;

FIG. 5 represents a downstream process block diagram for the separationand purification of the streams recovered from the fermentation reactorsof the apparatus of FIGS. 4A and 4B.

DETAILED DESCRIPTION

Referring to FIG. 1 , an apparatus 10 according to aspects describedherein, integrates two separate, distinct membrane units 11 and 12within a reactor 13. Reactor 13 is advantageously a reactor forconversion of a substrate 14, in particular a biomass substrate, to auseful product such as an ester or amide, in the presence of a catalyst,advantageously a biocatalyst, such as microorganisms or enzymes. Reactor13 comprises a reactor vessel 131 containing a reaction liquid 132including (partially) converted and non-converted feedstock, andoptionally the catalyst. Substrate 14 is advantageously continuouslysupplied to the reactor vessel 131 of reactor 13 through a supply duct141 via a pump 142. The substrate 14 advantageously comprises substratecompounds for the catalyst for carrying out the conversion reactions.

The catalyst is advantageously housed in the reactor 13 (reactor vessel131), and may or may not be immobilised therein. The catalyst isadvantageously mobile in the reactor 13, e.g. it is mixed or suspendedin the reaction liquid. Reaction products are advantageouslycontinuously or intermittently (e.g., after depletion of a substrate)removed from the reactor 13 through membrane units 11 and 12. Each ofthe membrane units 11 and 12 is advantageously configured to recover orwithdraw specific reaction products. Either one, or both the membraneunits 11 and 12 advantageously allow for retaining the catalyst in thereactor 13.

A first membrane unit 11 may be configured to withdraw a first stream 15from reactor 13. Membrane unit 11 advantageously comprises semipermeablemembranes for producing the first stream 15 as a permeate stream fromthe reaction liquid 132 in the reactor 13. By way of example, membraneunit 11 is configured as a filtration unit, comprising filtrationmembranes. Membrane unit 11 is coupled to an outlet duct 111 at thepermeate side. A pump 112 in communication with the outlet duct 111 maybe configured for installing a desired pressure difference across themembranes of membrane unit 11.

The first stream (permeate) 15 advantageously comprises, or consists ofa desired product to be recovered, such as an ester or an amidecompound. The desired product may be formed through conversion processesoccurring in the reactor 13, e.g. esterification and amidationreactions. Additional compounds present in reaction liquid 132 maypermeate through the membrane unit. The desired product may be recoveredfrom the first stream 15 through appropriate downstream processing, e.g.by distillation. Unconverted substrates may permeate through themembrane unit 11. These permeated substrates can be recycled to thereactor 13 after separation from the product to improve substrateutilization.

The membranes of membrane unit 11 are advantageously filtrationmembranes. Specific examples of suitable filtration membranes aremicrofiltration and ultrafiltration membranes. Another example of usefulfiltration membranes are nanofiltration membranes.

A second membrane unit 12 may be configured to withdraw a second stream16 from reactor 13. The second membrane unit 12 is advantageouslyconfigured for withdrawing the second stream 16 through pervaporation(or liquid-gas extraction) or liquid-liquid extraction. To this end, thesecond membrane unit 12 may comprise one or more semipermeablemembranes. In a first alternative, the second membrane unit 12 may beprovided as a pervaporation unit, comprising semipermeable membraneswhich are advantageously suitable for use in pervaporation processes.Alternatively, the second membrane unit 12 may be provided as a membranecontactor unit, comprising contactor membranes suitable forliquid-liquid extraction.

In one embodiment, a pervaporation unit separates the second stream 16from the medium in the reactor through permeation and evaporation of thesecond stream 16. In liquid-liquid extraction, a contactor membrane isused, over which a liquid phase is made to circulate at the permeateside. A difference in solubility or a concentration gradient providesthe driving force to generate a mass transfer of selective compoundsacross the membranes, hence forming the second stream 16. The secondmembrane unit 12 is coupled to an outlet duct 121 at the permeate sideof the unit. A pump 122, e.g. a vacuum pump in case of a pervaporationunit, may communicate with the outlet duct 121 side of the secondmembrane unit 12 to maintain a desired (partial vacuum) pressure level,or circulating flow (in case of liquid-liquid extraction).

The second stream 16 may comprise or consist of the compound, such asn-butanol in the exemplified (ABE) fermentation process or the secondstream 16 may comprise or consist of a by-product of conversionreactions occurring in the reactor 13, such as water and/or alcohols inthe exemplified enzymatic production of esters or amides. The by-productmay be an inhibitory compound which is formed from the conversionreactions, such as water and/or an alcohol, e.g. methanol in the examplebelow. An inhibitory compound refers to a compound which preventsfurther conversion of the substrate to the desired product to take placein reactor 13, in particular because of an equilibrium being reachedbetween the reagents, e.g. the substrate, and the reaction products. Byremoving the inhibitory compound, a rate of formation of the desiredproducts can be increased. Furthermore, by removing the inhibitorycompound, the catalyst may be protected from inactivation.

According to an aspect, the membranes of the first membrane unit 11 andthe membranes of the second membrane unit 12 are arranged inside thereactor 13. The membranes are advantageously at least partially andpreferably fully immersed in the reaction liquid of the reactor. Inparticular, these membranes are arranged inside the vessel 131 of thereactor.

A pervaporation or membrane contactor unit integrated within the reactorvessel simplifies the requirements for temperature and concentrationgradient control. Temperature gradients are minimized, and concentrationgradients over a surface of the membranes can easily be minimized byappropriately maintaining the reaction liquid 132 in motion relative tothe second membrane unit 12. A same reasoning may apply to a membranefiltration unit, such as the first membrane unit 11.

According to an aspect, and referring to FIGS. 2A-B, the membranes ofunits 11 and 12 are moveably arranged within the reactor 13. Inparticular, the membranes of units 11 and 12 are arranged to moverelative to the reactor 13 (reactor vessel 131). Each of the first andsecond membrane units 11, 12 may comprise a support frame 113, 123respectively which is pivotally arranged relative to reactor vessel 131.Support frames 113, 123 may be configured to turn on pivot axes 114, 124fixed to the reactor vessel 131, such as through a rotating oroscillating motion.

Respective membranes 115, 125 of the first and second membrane units 11,12 are mounted to the respective support frames 113, 123. The membranesare advantageously fixedly attached to the respective support frames.Each of the membranes 115, 125 comprise a first, outer surface in(direct) contact with, and advantageously immersed in the reactionliquid 132, and an opposite, second (inner) surface which communicateswith the respective outlet duct 111, 121, e.g. through an appropriatemanifold, which may be integrated in frame 113, 123. The membrane 115,125 advantageously provides for transport of compounds from the outersurface to the inner surface, while other compounds may be retained orrejected at the outer surface. The membranes 115, 125 are advantageouslyhollow fibre membranes or tubular membranes, even though planarmembranes, so called flat sheet membranes, and which may be arrangedflat (e.g. to act like impellers) or may be spirally wound, can be usedas well. The support frames 113, 123 and the disposition of themembranes 115, 125 thereon may have any desired configuration. Specific,non-limiting examples of such a configuration are support frames formedas radial brackets (as shown in FIG. 2A), concentric rings, bracketswinding spirally about the pivot axis, etc.

When the support frames 113, 123 with the membranes 115, 125 are turnedon axes 114, 124, the reaction liquid is advantageously mixed. Thesupport frames and membranes therefore may be used in replacement of, oradditional to impellers in the reactor. This minimizes concentration andtemperature gradients in the vessel, minimizes concentrationpolarization effects on the surface of the membranes and/or reducesfouling of the membranes 115, 125. The motion of support frames 113, 123may be continuous or intermittent. Specific examples of this motion area continuous rotation on axes 114, 124, and an oscillating motion, e.g.back and forth on axes 114, 124, advantageously over an angle rangingbetween 120° and 240°, e.g. 180°. An actuator, such as an electricmotor, possibly arranged outside the reactor vessel 131, may be coupledto the axis 114 and/or 124 to provide the pivoting motion.

FIG. 3 shows an alternative configuration of a reactor 33. Reactor 33differs from reactor 13 in that the membrane units 11, 12 are mounted ona common support frame 333, which is pivotally arranged on axis 314fixed with respect to reactor vessel 131. Support frame 333advantageously comprises first brackets 313 onto which the membranes 115relating to the first membrane unit 11 are mounted, and second brackets323 onto which the membranes 125 relating to the second membrane unit 12are mounted. The first and second brackets may be disposed as desired onpivot axis 314. By way of example, the first and second brackets may bedisposed alternatingly about axis 314. Each one bracket 313, 323advantageously comprises a collector manifold for collecting therespective first and second streams 15, 16 from the membranes, andcommunicating with the corresponding outlet duct 111, 121.

As with reactor 13, the support frame 333 of reactor 33 may beconfigured to turn on axis 314 with any desired motion, e.g.(continuous) rotation or oscillation. The shape of the support frame isnot particularly limited, and any suitable shape and/or disposition ofthe brackets 313, 323 may be used. Possible configurations for thesupport frame and which can be used in the reactors described herein,are described in US 2009/0034358 to Brod et al. and U.S. Pat. No.8,328,167 to Kauling et al. It should be noted that in the abovedocuments, the rotating membrane units are configured for gassing ofliquids, whereas in the present description the rotating membrane unitsare configured for withdrawing two distinct streams from the reactormedium.

The support frames 113, 123 of the first and second membrane units 11,12, or the support frame 333 placed inside the reactor vessel 131, areadvantageously moved relative to the reactor, e.g. by imparting apivoting motion on axis 114, 124 or 314 oscillating back and forth overa predetermined angle, e.g. 180° or smaller.

The membranes 115, 125 mounted on the respective support frame are incontact with the reactor medium. As the membranes move integrally withthe support frame, a relative motion between the reactor medium and themembranes is sustained. In the examples of FIGS. 2A-B and 3, the (hollowfibre) membranes have longitudinal axes oriented parallel to the pivotaxes 114, 124, 314, and therefore are oriented perpendicular to theplane of motion. These configurations may be effective in maintaining asufficient level of cross flow of the reactor medium over the externalsurface of the membranes.

It will be convenient to note that filtration membranes are just oneexemplary type of membranes that can be used in the apparatuses andprocesses described herein, e.g. in the first membrane unit 11. Otherpossible membranes may be configured to entrain a selective masstransfer across the membranes via mechanisms other than differentialpressure and/or characteristic pore size, such as though not limited to:characteristic attraction of specific charge types (e.g. an ion exchangemembrane), selective sorption, or solution or diffusion characteristics,e.g. membrane contactors.

Production of Esters or Amides

The reactor configurations described above in relation to FIGS. 1-3 areadvantageously used for processes involving forming esters or amides.

According to one aspect, the above reactor configurations are used in aprocess of forming an ester, in particular a chiral ester. Differentmethods for forming esters exist, and all of them are in principlecontemplated in the present description. One method of forming estersinvolves direct esterification. An alcohol and an organic acid, e.g. acarboxylic acid, are used as substrates and made to react to form theester and water. Another method involves transesterification. An alcoholand an ester, e.g. methyl ester, are used as substrates and are made toreact to form the ester and an alcohol, e.g. methanol. Other possiblemethods of forming esters involve alcoholysis of acyl chlorides or acidanhydrides.

Methods according to aspects described herein are particularlyinteresting for ester production where one and/or both substrates arevolatile and/or forms azeotropes with methanol or water. In such cases,nitrogen stripping is rendered complicated due to downstream processcomplications. Examples of useful esters that may be produced in methodsdescribed herein are: isopropyl esters, methacrylate esters and acrylateesters.

According to another aspect, the above reactor configurations are usedin a process of forming an amide, in particular a chiral amide, inparticular an organic amide. Different methods for forming amides exist,and all of them are in principle contemplated in the presentdescription. In one method of forming amides, an advantageously organicamine and an organic acid, e.g. a carboxylic acid, are used assubstrates and made to react to form an (organic) amide and water. Otherpossible methods involve using acid anhydrides or acyl chlorides.

Methods according to aspects described herein are particularlyinteresting for production of amides where one of and/or both thesubstrates are volatile and/or form azeotropes with methanol/water. Insuch cases, nitrogen stripping is rendered complicated due to downstreamprocess complications. Examples of useful processes include amideproduction processes where isopropyl amine or n-propyl amine is used assubstrate, or where (meth)acrylic acid, or (meth)acrylate esters areused as substrates.

The substrates are supplied to reactor 13 or 33. Substrate pump 142 maybe configured to supply substrates in controlled amounts to the reactor.Substrates may be pre-mixed prior to being supplied to the reactor, orthey may be fed separately to the reactor. A catalyst may be provided inthe reactor, either immobilized or freely suspended in the reactor. Thecatalyst is advantageously a biocatalyst, and processes described hereinare advantageously biocatalytic processes. The (bio)catalystadvantageously comprises or consists of an enzyme, such as a lipase oran esterase. Examples of useful catalysts include lipases from Candidaantarctica, from Burkholderia species, from Fervidobacterium nodosum,from Starmerella bombicola. A commercial name of an immobilised lipaseis Novozym® 435 (Novozymes, Denmark) which is immobilised on acrylicresin. The enzyme, such as the lipase, may be freely suspended in thereactor or may be immobilized on a carrier. The (bio)catalyst may be amicroorganism which may catalyze the reactions through an enzymecontained therein.

The substrates, e.g. supplied through stream 14, react in the reactor,possibly in the presence of the (bio)catalyst, to form the ester or theamide, and water or an alcohol, which build up in the reaction liquid132. Reaction conditions in the reactor are advantageously mild, andtemperature of the (reaction liquid in the) reactor may be maintained atbetween 30° C. and 70° C., advantageously between 40° C. and 65° C.,advantageously between 50° C. and 60° C. Advantageously, no (organic)solvents are used in the reaction liquid 132 to form the ester or theamide.

In the first membrane unit 11 a suitable pressure difference across themembranes 115 (the transmembrane pressure) is advantageously applied,e.g. via pump 112. This will withdraw a first stream (permeate) from thereaction liquid which is collected in permeate channels (e.g., theinternal lumens of membranes 115) of the membrane unit 11 and furtherevacuated via a collector manifold to the outlet duct 111. Throughsuitable selection of the type of membrane 115 (e.g., microfiltration,ultrafiltration, etc.), specific compounds may be selectively recoveredfrom the reaction liquid, e.g. on the basis of molecule size. Thesecompounds advantageously comprise the ester or the amide that isobtained through reaction in the reactor. Possibly, a portion of thesubstrate(s) may pass through the membranes 115. Membranes 115 may beselected to block passage of the (bio)catalyst, which will be retainedin the reactor.

The permeate collected by the membranes 115 forms a first stream 15,which may be further processed via an appropriate downstream processingto separate the different compounds from which it is composed. Thedesired ester or amide can e.g. be recovered from stream 15 bydistillation. Other compounds (e.g. the substrates) may be recovered,and may be recycled to the reactor 13, 33.

The membranes 125 of the second membrane unit 12 will withdraw a secondstream 16 from the reaction liquid. The second stream 16 may comprisemore than one compound originating from the reaction liquid. At leastone of these compounds is advantageously different from the compoundscollected in the first permeate by membranes 115 of the first membraneunit. In the instant embodiment the second stream advantageouslycomprises reaction (by-)products such as water or the alcohol, which arewithdrawn from the reaction liquid 132 so as to shift the reaction tothe right hand side and increase product titres. The second stream 16may be condensed to a liquid phase and may be separated into itsseparate compounds by an appropriate downstream processing.

Pervaporation membranes 125 may be porous or nonporous membranesallowing a selective mass transfer driven by a partial vapor pressuregradient between substrate and permeate side. In nonporous membranes, asorption-diffusion-desorption process is sustained through the membrane.Membranes for pervaporation are typically thin film composite membranes,comprising a separation layer defining the membrane characteristicsprovided on a porous support. Materials for the separation layer usefulfor pervaporation purposes may be made from a polymer material, azeolite, a ceramic material or combinations thereof (e.g., polymermembranes with zeolite or ceramic filler particles). The membranes maybe either hydrophilic, or organophilic (hydrophobic). Specific examplesof useful hydrophilic membranes are made of polyvinyl alcohol, A-type(NaA) or Y-type (NaY) zeolites, or (hybrid) silica. Specific examples ofuseful hydrophobic membranes are made of polydimethylsiloxane (PDMS) orZSM-5 (MFI) zeolite.

Hydrophilic pervaporation membranes are advantageously used forwithdrawing water from the reaction liquid. For withdrawing the alcoholproduct from the reaction liquid, organophilic pervaporation membranesmay be used. Alternatively, hydrophilic membranes may be used towithdraw the alcohol product.

Membranes used in membrane contactors may be porous or nonporousmembranes. In non-porous membranes, a sorption-diffusion-desorptionprocess is sustained through the membrane. Also here, membranes aretypically thin film composite membranes. Materials for the separationlayer useful for membrane contactor purposes may be made from a polymermaterial, a zeolite, a ceramic material or combinations thereof.

One advantage of the apparatuses and processes described herein is thatthey are inherently safer because no associated (external) loops withhigh cross flows are involved. There is no or less external piping whichmay be prone to leakage and/or which may expose maintenance operators to(potentially) toxic products. A further advantage is that it has a smallfootprint, taking much less space in comparison to prior art designs.Yet an additional advantage is that due to the integration of themembrane units 11 and 12 within the reactor, required pumping energy isgreatly reduced.

It will be convenient to note that additional membrane units may beintegrated in the reactor, similarly to the principles for the first andsecond membrane units 11, 12 described herein. By way of example, athird membrane unit may be provided in the reactor, either on a separatesupport frame, or integrated on the support frame of either or both thefirst and the second membrane units. The support frame of the membranesof the third unit may be pivotally arranged relative to the reactor, oralternatively may be fixed within the reactor. The third membrane unitmay be configured for dosing liquid or gaseous compounds to the reactionliquid, through suitable porous or nonporous membranes. Additionally, afourth, fifth and even further membrane units may be provided.

It will be convenient to note that, although the reactor 13 is describedherein as formed of a single vessel (e.g., a single stage reactor), thisis no requirement and apparatuses and methods described herein areapplicable to multi-stage reactors. A multi-stage reactor typicallycomprises a plurality, e.g. two, three or even more reactor vesselsarranged in series or in cascade. In such cases, the first membrane unit11 and the second membrane unit 12 need not be arranged in a samereactor vessel, and may be arranged in different ones. Alternatively, itis possible to provide either one, or both the first membrane unit 11and the second membrane unit 12 in more than one reactor vessel.

Production of Organic Solvents

Referring to FIG. 4A, an apparatus 400 according to another aspectdescribed herein integrates two separate, distinct membrane units 11 and12 within a reactor 13. Reactor 13 is advantageously a reactor forconversion of a feedstock 14, in particular a biomass feedstock, to auseful product, in particular an organic solvent, or a mixture of aplurality of organic solvents. The conversion may be assisted by asuitable (bio)catalyst, such as a microorganism and/or an enzyme. Feed14 is advantageously continuously supplied to the reactor 13 through asupply duct 141 via a feed pump 142.

The conversion reaction(s) in present aspects advantageously refer tofermentation reactions, including fermenting a feedstock in the presenceof microorganisms, such as microorganisms of the Clostridium genus, inparticular Clostridium acetobutylicum. The fermentation reaction(s) areadvantageously all or in part carried out under anaerobic conditions.

Reactor 13 may be a single stage reactor, e.g. comprising a singlevessel in which the feedstock 14 is converted; or a multi-stage reactor,comprising a plurality of reactor vessels arranged in series or incascade, in which the conversion/fermentation reactions are carried outin a stepwise manner. By way of example, the reactor can be a two-stagereactor, or a three-stage reactor, as shown in FIG. 4A. The three-stagereactor comprises a first reactor 431 serially coupled to a secondreactor 432, which in turn is serially coupled to a third reactor 433.The first reactor 431 comprises a first medium 137, which may comprisepartially converted feedstock 14 and may also comprise residualfeedstock that is not converted in the first reactor 431. Medium 137 isadvantageously continuously withdrawn from the first reactor andsupplied to the second reactor 432, e.g. via a pump 135. The secondreactor 432 comprises a second medium 138, in which the medium 137 ofthe first reactor, which may contain residual feedstock 14, is furtherreacted. The second medium 138 may already comprise desired reactionproducts, such as a mixture of ABE solvents. The second medium 138 isadvantageously continuously withdrawn from the second reactor andsupplied to the third reactor 433, in which residual feedstock, such asresidual carbohydrates, can further be converted in reactor medium 139.A third stream 17 may be withdrawn from the third reactor 433. It willbe convenient to note that any one or all of the media 137, 138, 139 maybe referred to as a fermentation broth.

Microorganisms may be present in any one or all of the first reactor431, the second reactor 432, and the third reactor 433. By way ofexample, in the first reactor 431, an acidogenic fermentation may takeplace. In the second and third reactors 432 and 433, a solventogenicfermentation may take place. The third reactor may allow for maximizingsolvent titers. The improved carbohydrate conversion will lower thesubstrate costs and the higher solvent titers will decrease the cost forfurther recovery of residual solvents. It will be convenient to notethat more reactor stages may be added as desired, or any one of thefirst reactor stage and the third reactor stage may be omitted.

The feedstock 14 may comprise any suitable biomass. Feedstock 14 mayoriginate from or comprise sugar cane, corn mash, or wheat. Thefeedstock 14 advantageously comprises carbohydrates, in particularhydrolysates, such as C5/C6 carbohydrates (such as starch, glucose,xylose), lignocellulosic hydrolysates, or hydrolysates from pulp andpaper industry.

Advantageously, the fermentation reaction(s) in aspects of the presentdisclosure is (are) carried out at a temperature comprised between 30°C. and 45° C., advantageously between 30° C. and 40° C., advantageouslybetween 32° C. and 38° C., advantageously between 35° C. and 37° C. Thisis obtained by maintaining the medium in reactor 13 (e.g. either one ofthe first reactor 431, second reactor 432, third reactor 433, or anycombination thereof), at the temperature as indicated.

Advantageously, the pH of the medium in the reactor is maintainedbetween 4.0 and 6.0, advantageously between 4.0 and 5.5, advantageouslybetween 4.5 and 5.5, advantageously between 4.5 and 5.0.

Methods in aspects of the present description can be performed in abatch, fed-batch, or continuous manner, i.e. the feedstock 14 isprovided (or introduced) in the reactor on a batch, fed-batch, orcontinuous basis.

The microorganisms are advantageously housed in the reactor, and may ormay not be immobilised therein. Reaction products and possiblyadditional compounds, are advantageously continuously removed from thereactor through membrane units 11 and 12 as described hereinabove inrelation to apparatus 10. Either one of, or both the membrane units 11and 12 is advantageously configured to recover or withdraw specificcompounds. The membrane units 11 and 12 advantageously allow forretaining the microorganisms in the reactor.

In this embodiment the first stream (permeate) 15 is advantageouslywithdrawn so as to increase cell concentration (of dry cell weights) inthe reactor. This may advantageously result in an increase of feed(substrate) supply rates, solvent productivity and/or utilization ofxylose. Additionally, the filtration membranes of the first membraneunit advantageously allow for retaining microorganisms and otherpossible catalysts in the reactor medium. This allows for increasingcell/microorganism concentration in the reactor, which may improveproduct conversion and may allow for reducing residence times of thefeedstock in the reactor.

In this embodiment the second stream 16 may comprise or consist of areaction product, such as the organic solvent, or the mixture of organicsolvents. In the particular case of ABE fermentation, e.g. withClostridia strains, the second stream may comprise or consist of one ormore of, or consist of a mixture of: isopropanol, acetone, n-butanol andethanol, and possibly water.

In the particular case that the second membrane unit 12 is apervaporation unit, carbon dioxide (CO₂) generated by the fermentationreactions may advantageously be collected in the second stream. Due tothe generally lower pressure at the filtrate side of the filtrationmembranes of the first membrane unit 11, CO₂ is locally oversaturated inthe filtrate side and leads to CO₂ bubble formation in the filtrateside. This distorts liquid flows and leads to a difficult control of theresidence time in continuous fermentations, which is required to ensuretarget productivities. The pervaporation membranes for solvent recoveryoperated in parallel with the filtration membranes do not only decreasethe solvent concentration in the fermentation broths, they also removeCO₂. This results in an improved control of the residence time in thefermentation reactors by avoiding CO₂ bubble formation at the filtrateside of the filtration membranes.

Referring to FIG. 4B, an alternative apparatus 500 and related processscheme is provided. The apparatus and process scheme of FIG. 4B differsfrom the one of FIG. 4A in that a third membrane unit 18 is integratedin a similar way in the reactor 13, advantageously in the same reactorvessel as one or both of the other two membrane units 11 and 12. Thethird membrane unit 18 is configured to remove CO₂, H₂ and optionallyother non-condensable gases. The third membrane unit 18 may beconfigured to operate as a membrane contactor, advantageously operatingat a partial vacuum pressure at the permeate side. Suitable partialvacuum permeate pressures range between 75 mbar and 500 mbar,advantageously between 100 mbar and 400 mbar. At these relatively highpermeate pressures (as compared to standard vacuum conditions), anegligible transfer of solvents occurs. Any solvents that may betransported through the membranes of the third membrane unit 18 may becondensed in a condenser 182 arranged downstream of a vacuum pump 181.The stream of solvents withdrawn through the third membrane unit 18 maybe collected as a fourth stream 19 following removal of thenon-condensable gases as a separate stream 183. Such a third membraneunit 18 can decrease overall vacuum costs. The presence ofnon-condensable gases greatly affects the operating costs of a vacuumpump, as shown in Van Hecke, W. and De Wever, H. in J. Membr. Sci.(2017), 540 (321-332). Hence, removal of the non-condensable gases in aseparate loop at higher permeate pressures avoids excessive costsrelated to the vacuum (operating costs and number of vacuum pumps) inthe second membrane unit 12.

According to an aspect, the membranes of the first membrane unit 11 andthe membranes of the second membrane unit 12 are arranged inside thereactor 13, advantageously at least partially immersed in a medium 138of the reactor. In particular, these membranes are arranged inside avessel of the reactor. The reactor may be any one, or a plurality of thefirst reactor 431, the second reactor 432, and the third reactor 433. Inthe examples of FIGS. 4A-B, the membranes of the first and secondmembrane units are arranged in the vessel 131 of the second reactor 432,advantageously at least partially and advantageously fully immersed inthe second reactor medium 138. In an alternative configuration, themembranes of one or both the first and second membrane units may bearranged in the vessel of the first reactor 431, and advantageously beimmersed in the first reactor medium 137. By way of example, themembranes of the first membrane unit 11 may be arranged in the firstreactor 431, while the first membrane unit is arranged in the secondreactor 432. Yet alternatively, an additional membrane unit operatingsimilarly to the first membrane unit 11 may be arranged in the firstreactor 431

A pervaporation or liquid-liquid extraction unit integrated within thereactor vessel simplifies the requirements for temperature andconcentration gradient control. Temperature gradients are minimized, andconcentration gradients over a surface of the membranes can easily beminimized by appropriately maintaining the reactor medium 432 in motionrelative to the second membrane unit 12. A same reasoning applies to amembrane filtration unit, such as the first membrane unit 11.

A fifth stream can be withdrawn from the medium as a bleed. The fifthstream may be smaller in comparison to the first stream and/or thesecond stream. The fifth stream advantageously allows for keeping a cellconcentration constant in the reactor and hence, enables to operate thereactor in steady-state conditions. It will be convenient to note thatthe fifth stream need not, and typically will not be withdrawn through amembrane, since the purpose here is to remove part of the larger sizedcompounds (e.g., cells) from the reactor medium.

According to an aspect, the membranes of units 11 and 12 are arranged tomove relative to the reactor 13 as already indicated above in relationto FIGS. 2A-B and FIG. 3 . In particular, the membrane units 11 and 12may be arranged in vessel 131 of the second reactor 432 and be arrangedto move relative to the vessel.

It will be convenient to note that the first and second membrane unitsmay each be disposed in any one of the available reactors 431, 432, 433containing a reactor medium. By way of example, the support frame 113and membranes 115 of the first membrane unit 11 may be arranged in thethird reactor 433, while the support frame 123 and membranes 125 may bearranged in the second reactor 432.

In the first membrane unit 11, a suitable pressure difference across themembranes 115 (the transmembrane pressure) is advantageously applied,e.g. via pump 112. This will withdraw a first stream 15 from the reactormedium which is collected in permeate channels (e.g., the internallumens of membranes 115) of the membrane unit 11 and further evacuatedvia a collector manifold to the outlet duct 111. Through suitableselection of the type of membrane 115 (e.g., microfiltration,ultrafiltration, etc.), specific compounds may be selectively recoveredfrom the reactor medium, e.g. on the basis of molecule size. Membranes115 may be selected to block passage of the microorganisms present inthe reactor, which will be retained in the reactor. As a result, cellconcentration in the reactor(s) is increased, which will increaseconsumption of feedstock and therefore increase production rate of theorganic solvent(s). By way of example, even though Clostridial strainsare known to consume C5 carbohydrates, consumption rates are observed tobe low in comparison to C6 consumption rates. This hampers solventproductivities and leads to bulky fermentors. A filtration membrane unitallows cell retention and by consequence will lead to improved xyloseconversion.

As shown in FIG. 4A and FIG. 4B, the first stream 15 may be introducedin another reactor stage, e.g. a downstream stage, such as the thirdreactor 433, or may be further processed to separate the individualcompounds by an appropriate downstream processing, e.g. by distillation.

The pervaporation or contactor membranes 125 of the second membrane unit12, when applying a suitable partial vacuum or reduced pressure at theinternal membrane surface (permeate side), e.g. via pump 122, willwithdraw a second permeate from the reactor medium which is collected inpermeate channels (e.g., the internal lumens of membranes 125) of themembrane unit 12 and further evacuated via a collector manifold to theoutlet duct 121 as the second stream 16. In case the second membraneunit 12 is arranged as a pervaporation unit, the second stream istypically collected at the internal face of membranes 125 as a vapor.The second stream 16 may comprise more than one compound. The secondstream advantageously comprises volatile organic compounds, such as theorganic solvent(s), and may comprise water. Withdrawing the organicsolvent(s) from the reactor medium alleviates product toxicity andimproves the water balance by increasing the carbohydrate utilization.The second stream 16 may be condensed to a liquid phase, e.g. throughcondenser 161, and may be separated into its separate compounds by anappropriate downstream processing.

It will be convenient to note that additional membrane units may beintegrated in the reactor, similarly to the principles for the first andsecond membrane units 11, 12 described herein. Referring to FIGS. 4A and4B, a fifth membrane unit 20 may be provided in the downstream reactorstage 433. The fifth membrane unit may be similar as the first membraneunit 11, e.g. arranged as a filtration unit comprising microfiltrationor ultrafiltration membranes, or alternatively may be similar to thesecond membrane unit 12.

Furthermore, the third membrane unit 18 may be provided in the reactor,either on a separate support frame, or integrated on the support frameof either or both the first and the second membrane units. The supportframe of the membranes of the third unit may be pivotally arrangedrelative to the reactor, or alternatively may be fixed within thereactor. Yet further membrane units may be provided, e.g. configured fordosing liquid or gaseous compounds to the reactor medium, throughsuitable porous or nonporous membranes.

The reactor configurations described above in relation to FIGS. 4A-B areadvantageously used for processes involving forming one or a mixture oforganic solvents, as described herein, such as ABE. Conventionaldownstream processing may be applied to the second stream 16 and/or thethird stream 17 to obtain the organic solvent at desired purity grades.One specific example of a possible downstream process for the secondstream 16 and the third stream 17 will now be described in relation toFIG. 5 , in particular for the case in which the second stream 16originates from a membrane unit 12 being a pervaporation unit. Thesecond stream 16 is supplied as feed to a first distillation column 34,possibly as a condensate following passing through a condenser 161 (seeFIG. 4A-B). The second stream 16 is distilled in column 34 to produce anoverhead stream 8, enriched in a first range of solvents, and a bottomsstream 7 which may be liquid, depleted in the first range of solvents.Distillation column 34 is advantageously a multistage distillationcolumn, such as comprising a number of theoretical stages rangingbetween 6 and 35.

The third stream 17, or at least a portion thereof may also be fed tothe first distillation column 34. To this end, third stream 17 can firstbe sent to a stripper, e.g. a steam stripper 36. In the context of thepresent description, a steam stripper refers to a beer stripper or steamdistillation apparatus, known by those skilled in the art. The thirdstream 17 may be centrifuged for cell/particle removal prior to sendingthe (cell/particle-free) effluent to the stripper. In addition, oralternatively, third stream 17 may be heated, e.g. by passing throughheat exchangers 37, 38, prior to being fed to the stripper. By way ofexample, heat exchanger 37 may be configured to heat stream 17 to atemperature comprised between 75° C. to 85° C., after which the stream17 may be further heated by heat exchanger 38, e.g. to a temperaturecomprised between 90° C. to 95° C., and afterwards sent to the steamstripper 36. Steam stripper 36 produces a top (overhead) stream 4 whichis fed to the first distillation column 34, where it is distilled inconjunction with the second stream 16 to produce bottoms stream 7 andoverhead stream 8.

Bottoms stream 7, exiting the first distillation column 34 may comprisetwo phases, a solvent rich phase and an aqueous phase. In one specificexample, the solvent rich phase comprises n-butanol and the aqueousphase comprises water. These two phases are subsequently separated in asuitable separator. By way of example, bottoms stream 7 is fed to adecanter 35, where stream 7 is separated in the solvent rich phase 71,and the aqueous phase 72. In ABE fermentative processes, the solventrich phase 71 advantageously is mainly formed of n-butanol, e.g. atleast 51% by volume. The aqueous phase 72 may comprise a lesser amountof n-butanol, e.g. less than 15% by volume, such as between 3% to 15% byvolume n-butanol.

A heat exchanger 40 may be arranged between the first distillationcolumn 34 and the decanter 35 to adjust a temperature of the bottomsstream 7 to a temperature suitable for decantation. A suitabletemperature for decantation depends on the products, advantageouslysolvents, that need to be separated and will be apparent for thoseskilled in the art. By way of example, the temperature of stream 7 uponfeeding to decanter 35 ranges between 35° C. and 45° C.

The solvent rich phase 71 is advantageously further purified, e.g. bydistillation. To this end, phase 71 may be fed to a second distillationcolumn 42, communicating with a first outlet of the decanter 35. Seconddistillation column 42 generates a bottoms stream 74 forming a firstsolvent, advantageously a substantially pure first solvent. In ABEfermentations, stream 74 advantageously comprises, or consists of(substantially pure) n-butanol. Advantageously, stream 74 consists ofn-butanol having a purity comprised between 99.0% (w/w) and 99.9% (w/w),advantageously between 99.5% (w/w) and 99.9% (w/w), advantageouslybetween 99.7% (w/w) and 99.9% (w/w), advantageously a purity of 99.8%(w/w).

The produced (substantially pure) n-butanol in aspects of the disclosurecan be used as an intermediate in chemical industry. For example, theproduced n-butanol can be used as a solvent, as a feedstock chemical inthe plastics industry, as an ingredient in formulated products such ascosmetics, as a food grade extractant in the food and flavour industry,as a fuel, or as a fuel additive. The overhead stream 73 exiting seconddistillation column 42 can be recycled back to the decanter 35 fordecantation.

The aqueous phase 72 exiting the decanter 35 as a bottoms stream isadvantageously further purified, e.g. by distillation. To this end,phase 72 can be sent to a third distillation column 43, communicatingwith a second outlet of the decanter 35. The third distillation column43 generates a bottoms stream 76 forming a substantially pure aqueousphase, depleted from organic solvent. Advantageously, stream 76comprises only trace amounts of (organic) solvents, advantageouslystream 76 comprises mainly water depleted from n-butanol. The thirddistillation column 43 generates an overhead stream 76 which can berecycled back to the decanter 35.

In an alternative embodiment, the aqueous phase 72 formed by decantationin the decanter 35 as a bottoms stream, can be sent to an extractionunit (not shown). In such an extraction unit, n-butanol is extracted outof water using a (bio)diesel or another fuel as extractant. This resultsin the production of a n-butanol enriched (bio)fuel, which can befurther used as such.

Overhead stream 8 of the first distillation column 34 may compriseamounts of organic solvents. In ABE fermentation, for example, stream 8may comprise a mixture of mainly acetone and ethanol. The obtainedmixture comprising acetone and ethanol can directly be used in furtherchemical reactions. Alternatively, overhead stream 8 may be furtherpurified/separated, e.g. by distillation to obtain a stream of(substantially pure) acetone and a separate stream of an azeotropicmixture of ethanol. To this end, overhead stream 8 can be sent to afourth distillation column 41, communicating with a second outlet of thefirst distillation column 34. The fourth distillation column 41generates an overhead stream 81 comprising, or consisting of a(substantially pure) second solvent and a bottoms stream 82 comprising athird solvent (and being depleted in the second solvent). In ABEfermentation, stream 81 advantageously comprises or substantiallyconsists of acetone. The obtained acetone in stream 81 may have a puritycomprised between 98.0% (w/w) and 99.9% (w/w), advantageously between98.5% (w/w) and 99.5% (w/w), advantageously between 99.0% (w/w) and99.5% (w/w). Stream 82 may be rich in ethanol. By way of example, stream82 may be an azeotropic mixture (or azeotropic solution) comprisingbetween 85% and 90% by volume ethanol and between 10% and 15% by volumewater, advantageously between 86% and 88% by volume ethanol and between12% and 14% by volume water, advantageously 87% by volume ethanol and13% by volume water.

1. An apparatus, comprising: a reactor, comprising a first reactorvessel, a substrate supply, a first outlet and a second outlet, afiltration unit comprising a first membrane having a first surfacecommunicating with the first reactor vessel and a second surface,opposite the first surface, communicating with the first outlet, and aliquid-liquid or liquid-gas extraction unit comprising a second membranehaving a third surface communicating with the first reactor vessel and afourth surface, opposite the third surface, communicating with thesecond outlet, wherein the first membrane and the second membrane arearranged inside the first reactor vessel, and wherein the first membraneand the second membrane are arranged to move relative to the firstreactor vessel.
 2. The apparatus of claim 1, wherein the filtration unitis configured to apply a first pressure difference between the firstsurface and the second surface, the first pressure difference beingconfigured to generate a permeate flow from the first surface to thesecond surface.
 3. The apparatus of claim 1, comprising wherein theliquid-liquid or liquid-gas extraction unit is configured to apply asecond pressure difference between the third surface and the fourthsurface, the second pressure difference being configured to recover aliquid compound in the first reactor vessel through a correspondingvapor at the fourth surface.
 4. The apparatus of claim 3, wherein theliquid-liquid or liquid-gas extraction unit is configured to apply apartial vacuum at the fourth surface.
 5. The apparatus of claim 1,wherein the first membrane is a microfiltration, ultrafiltration ornanofiltration membrane, and wherein the second membrane is a membranefor pervaporation or liquid-liquid extraction.
 6. The apparatus of claim1, comprising a first support frame and a second support frameassociated with the first membrane and the second membrane respectively,wherein the first and second support frames are pivotally arrangedrelative to the first reactor vessel.
 7. The apparatus of claim 6,wherein the first membrane and the second membrane are fixedly attachedto the respective first and second support frame.
 8. The apparatus ofclaim 6, comprising: a pair of pivot axes fixedly arranged to the firstreactor vessel, wherein the first and second support frames areconfigured to turn on a respective one of the pivot axes.
 9. Theapparatus of claim 6, comprising: a common pivot axis fixedly arrangedto the first reactor vessel, wherein the first and second support framesare configured to turn on the common pivot axis.
 10. The apparatus ofclaim 1, wherein the first membrane and the second membrane areconfigured to turn on respective pivot axes relative to the reactor,wherein the respective pivot axes are each arranged in a fixed positionrelative to the reactor.
 11. The apparatus of claim 1, wherein the firstmembrane and the second membrane are configured to turn on a commonpivot axis relative to the reactor, wherein the common pivot axis isarranged in a fixed position relative to the reactor.
 12. The apparatusof claim 1, comprising a third membrane unit arranged in the firstreactor vessel, wherein the third membrane unit is configured to operateas a membrane contactor.
 13. The apparatus of claim 12, wherein thethird membrane unit is configured to operate at a partial vacuumpressure between 75 mbar and 500 mbar at a permeate side of a membraneof the third membrane unit.
 14. The apparatus of claim 12, wherein thethird membrane unit comprises a vacuum pump and a condenser downstreamof the vacuum pump.
 15. The apparatus of claim 12, wherein the thirdmembrane unit comprises membranes arranged on a support frame, whereinthe support frame is arranged pivotally relative to the first reactorvessel.
 16. The apparatus of claim 12, wherein the third membrane unitcomprises membranes arranged on a support frame, wherein the supportframe is arranged fixed relative to the first reactor vessel.
 17. Theapparatus of claim 16, wherein the third membrane unit is configured asa filtration unit, a liquid-liquid extraction unit or a liquid-gasextraction unit.
 18. The apparatus of claim 1, wherein the reactorcomprises a second reactor vessel arranged downstream of the firstreactor vessel and a further membrane unit arranged in the secondreactor vessel.